Electronics have been incorporated into many portable devices such as computers, mobile phones, tracking systems, scanners, hearing aids, remote sensors, etc. One drawback to such portable devices is the need to include the power supply with the device. Portable devices typically use batteries as power supplies. Batteries must have sufficient capacity to power the device for at least the length of time the device is in use. Sufficient battery capacity can result in a power supply that is disproportionately heavy and/or large compared to the device. Accordingly, smaller and lighter energy storage devices (i.e., power supplies) are desired.
One such type of an energy-storage device is a solid-state, thin-film battery. Examples of thin-film batteries are described in U.S. Pat. Nos. 5,314,765; 5,338,625; 5,445,906; 5,512,147; 5,561,004; 5,567,210; 5,569,520; 5,597,660; 5,612,152; 5,654,084; and 5,705,293, each of which is herein incorporated by reference. U.S. Pat. No. 5,338,625 describes a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or first integrated power source for electronic devices.
Thin film batteries have been made in particular using silicon as a substrate, at least in part because of the reliability of this material and familiarity that manufacturers of small electromechanical devices (including integrated circuit manufacturers) have with silicon wafers. There continues to be a need for devices and methods that facilitate provision of reliable power supplies, particularly in small devices.